Anthraquinone dyes

ABSTRACT

The present invention relates to a compound of formula (I) wherein R 1  and R 3  are each independently of the other —NHR 5 , NHSO 2 R 5 , —NHCOR 5 , —OR 6  or —SR 7 , R 2  and R 4  are each independently of the other —OR 6  or —SR 7 , with the proviso that not all of the substituents R 1  to R 4  are —SR 7 , R 5  is hydrogen, alkyl, aryl, aralkyl or a group of formula —(C n H 2n X) m —H wherein X is —O—, —S—, —SO 2 —, —NH—, —NR 8 —, —CONH— or —CONR 8 — and R 8  is alkyl or aryl, n is a number from 2 to 6 and m is a number from 1 to 10, R 6  is aryl or heteroaryl and R 7  is alkyl, aryl, heteroaryl or a group of formula —(C n H 2n X) m —H wherein X is —O—, —S—, —SO 2 —, —NH—, —NR 8 —, COHN— or —CONR 8 — and R 8  is alkyl or aryl, to a process for the preparation thereof and to the use thereof in a method of producing mass-coloured plastics or polymeric colour particles.

The present invention relates to novel anthraquinone dyes, to a processfor the preparation thereof and to the use thereof in a method ofproducing mass-coloured plastics or polymeric colour particles.

Dyes, especially dyes of the anthraquinone series, are known formass-colouring plastics. For example there are described in U.S. Pat.No. 5,367,039 1,4,5,8-tetrasubstituted anthraquinones having(meth)acryloyl groups which can be copolymerised with vinyl monomers andare thus suitable for the production of coloured vinyl polymers.

The dyes used until now do not, however, meet the highest requirementsin terms of light fastness and, especially, thermostability.

There is accordingly a need for novel thermostable dyes that producecolorations having a high tinctorial strength and exhibiting lightfastness, especially high-temperature light fastness, and that have goodall-round fastness properties.

It has now, surprisingly, been found that the dyes according to theinvention substantially meet the above criteria.

The present invention accordingly relates to a compound of formula I

wherein

R₁ and R₃ are each independently of the other NHR₆, —NHSO₂R₅, —NHCOR₅,—OR₆ or —SR₇,

R₂ and R₄ are each independently of the other —OR₆ or —SR₇,

with the proviso that not all of the substituents R₁ to R₄ are —SR₇,

R₅ is hydrogen, alkyl, aryl, aralkyl or a group of formula—(C_(n)H_(2n)X)_(m)—H wherein X is —O—, —S—, —SO₂—, —NH—, —NR₈—, —CONH—or —CONR₆— and R₈ is alkyl or aryl, n is a number from 2 to 6 and m is anumber from 1 to 10,

R₆ is aryl or heteroaryl and R₇ is alkyl, aryl, heteroaryl or a group offormula —(C_(n)H_(2n)X)_(m)—H wherein X is —O—, —S—, —SO₂—, —NH—, —NR₈—,—CONH— or —CONR₈— and R₈ is alkyl or aryl.

The substituents R₁ and R₃ may be identical or different; preferably, R₁and R₃ are identical.

Likewise, R₂ and R₄ may be identical or different, but are preferablyidentical.

Any radical denoting alkyl may be a straight-chain or branched alkylradical that may be substituted by one or more hydroxy groups, aminogroups or halogen atoms.

Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,neopentyl, n-hexyl, n-heptyl, n-octyl, isooctyl, n-decyl and n-dodecyl.

Substituted alkyl groups include, for example, 2-hydroxyethyl,2-hydroxypropyl, 4-hydroxybutyl, 2-aminoethyl, 2-aminopropyl,4-aminobutyl, 2-chloroethyl, 2-bromoethyl and 4-chlorobutyl.

The aryl radicals designated R₅ to R₈ have preferably from 5 to 24,especially from 6 to 14, carbon atoms and may be substituted, forexample, by hydroxy, C₁-C₄alkyl, C₁-C₄alkoxy, C₁-C₄hydroxyalkyl, halogenor by the radical —NH—CO—R wherein R is amino, C₁-C₄alkyl, unsubstitutedphenyl or phenyl substituted by hydroxy, C₁-C₄alkyl, C₁-C₄alkoxy,C₁-C₄-hydroxyalkyl or by halogen.

Examples of suitable aryl groups include phenyl, tolyl, mesityl, isityl,2-hydroxyphenyl, 4-hydroxyphenyl, 2-chlorophenyl, 4-chlorophenyl,2,6dichlorophenyl, 2-aminophenyl, 3-aminophenyl, 4-aminophenyl,4-methoxyphenyl, 4ethoxyphenyl, 4-acetylaminophenyl, naphthyl andphenanthryl.

Aralkyl groups as R₅ have preferably from 6 to 30, especially from 7 to12, carbon atoms and may be unsubstituted or substituted by one or moreC₁-C₄alkyl groups, C₁-C₄alkoxy groups, halogen atoms or —NH—CO—Rradicals wherein R is amino, C₁-C₄alkyl, unsubstituted phenyl or phenylsubstituted by C₁-C₄alkyl, C₁-C₄alkoxy or by halogen.

Examples of suitable aralkyl groups include benzyl, 2-phenylethyl,tolylmethyl, mesitylmethyl and 4chlorophenylmethyl.

Heteroaryl as R₆ or R₇ contains preferably 4 or 5 carbon atoms and oneor two hetero atoms from the group O, S and N. It may be, for example,pyrrolyl, furyl, thiophenyl, oxazolyl, thiazolyl, pyridyl, pyrazinyl,pyrimidinyl, pyridazinyl, indolyl, purinyl or quinolyl.

In formula I, R₁ and R₃ are preferably —NHR₅ or —SR₇.

Preference is given to compounds of formula I wherein R₁ and R₃ are—NHR₅ or —SR₇ and R₅ and R₇ are aryl or hydroxyalkyl.

Special preference is given to compounds of formula I wherein R₁ and R₃are —NHR₅ or —SR₇, R₅ is phenyl, mesityl or 2-hydroxyethyl and R₇ isphenyl.

R₂ and R₄ in formula I are preferably —SR₇.

In especially preferred compounds of formula I, R₂ and R₄ are —SR₇wherein R₇ is aryl or hydroxyalkyl, especially phenyl or 2-hydroxyethyl.

Special preference is given to compounds of formulae Ia-Ic

The compounds of formula I can be prepared, for example, from1,3,5,7-tetrabromo-anthraquinone by reaction with suitable nucleophiles.In that reaction, advantageously in a first step the radicals R₁ and R₃,which are preferably identical, are introduced into the reactive1,5-positions. In a further nucleophilic substitution reaction, theremaining bromine atoms in the 3,7-positions are replaced by R₂ and R₄,which are likewise preferably identical. When the radicals R₁ to R₄ areidentical, the reaction can also be carried out in a single step.

1,3,5,7-Tetrabromoanthraquinone can, for example, be prepared in twosteps from 1,5-diaminoanthraquinone. Bromination in aqueous hydrochloricacid yields 1,5diamino-2,4,6,8-tetrabromoanthraquinone (R. Scholl, F.Eberle, W. Tritsch: Monatshefte für Chemie 32, 1055 (1911)), which canbe converted, by diazotization and subsequent reduction, into1,3,5,7-tetrabromoanthraquinone (H. Kopf, J. Fuchs, K. H. Eisenmann:Annalen der Chemie 585, 178 (1954); F. Ullmann, O. Eiser: ChemischeBerichte 49, 2154 (1916)).

The invention relates also to a process for the preparation of acompound of formula I which comprises reacting1,3,5,7-tetrabromoanthraquinone with a compound R₁—H or with a mixtureof the compounds R₁—H and R₃—H in a first reaction step, and thenreacting the so-prepared intermediate with a compound R₂—H or with amixture of the compounds R₂—H and R₄—H, R₁, R₂, R₃ and R₄ being asdefined hereinabove.

The compounds R₁—H, R₂—H, R₃—H and R₄—H are known or can be prepared ina manner known per se.

The present invention relates also to a method of producingmass-coloured plastics or polymeric colour particles which comprisesmixing a high molecular weight organic material and a tinctoriallyeffective amount of at least one compound of formula (I).

The colouring of the high molecular weight organic substances using thedye of formula (I) is carried out, for example, by using roll mills,mixing apparatus or grinding apparatus to admix such a dye with suchsubstrates, the dye being dissolved or finely distributed in the highmolecular weight material. The high molecular weight organic materialwith the admixed dye is then processed according to methods known perse, such as, for example, calendering, compression moulding, extrusion,coating, spinning, pouring or injection moulding, as a result of whichthe coloured material acquires its final form. Admixture of the dye canalso be effected immediately prior to the actual processing step, forexample by simultaneously continuously feeding, directly into the intakezone of an extruder, a solid, for example pulverulent, dye and agranulated or pulverulent high molecular weight organic material and,where appropriate, also other ingredients, such as additives, theconstituents being mixed in just before being processed. Generally,however, preference is given to mixing the dye into the high molecularweight organic material beforehand, since more uniformly colouredsubstrates can be obtained.

In order to produce non-rigid shaped articles or to reduce theirbrittleness, it is frequently desirable to incorporate so-calledplasticisers into the high molecular weight compounds prior to shaping.There may be used as plasticisers, for example, esters of phosphoricacid, phthalic acid or sebacic acid. In the method according to theinvention, the plasticisers can be incorporated into the polymers beforeor after the incorporation of the colorant. It is also possible, inorder to achieve different colour shades, to add to the high molecularweight organic substances, in addition to the dye of formula (I), alsoother pigments or other colorants in the desired amounts, optionallytogether with further additives, for example fillers or siccatives.

Preference is given to the colouring of thermoplastic plasticsespecially in the form of fibres. Preferred high molecular weightorganic materials that can be coloured in accordance with the inventionare very generally polymers having a dielectric constant ≧2.5,especially polyester, polycarbonate (PC), polystyrene (PS), polymethylmethacrylate (PMMA), polyamide, polyethylene, polypropylene,styrene/acrylonitrile (SAN) or acrylonitrile/butadiene/styrene (ABS).Polyester and polyamide are especially preferred. More especiallypreferred are linear aromatic polyesters, which can be obtained bypolycondensation of terephthalic acid and glycols, especially ethyleneglycol, or condensation products of terephthalic acid and1,4-bis(hydroxymethyl)cyclohexane, for example polyethyleneterephthalate (PET) or polybutylene terephthalate (PBT); alsopolycarbonates, e.g. those obtained fromα,α-dimethyl4,4-dihydroxy-diphenylmethane and phosgene, or polymersbased on polyvinyl chloride and also on polyamide, for example polyamide6 or polyamide 6.6.

When the compounds of formula (I) according to the invention contain atleast two NH, OH or SH groups, mixing the dye with the monomers andincorporation thereof in the form of a comonomer directly into thepolymer skeleton is possible, provided that the monomers containreactive groups that react with the active hydrogen atoms of the NH, OHor SH groups. Examples of such monomers include epoxides (epoxy resins),isocyanates (polyurethanes) and carboxylic acid chlorides (polyamides,polyesters).

The invention accordingly relates also to a method of producingmass-coloured plastics or polymeric colour particles that comprisescausing a mixture comprising at least one monomer that contains at leastone NH-, OH- or SH-reactive group and is capable of polymerisation,polyaddition or polycondensation reactions to react with at least onecompound of formula I containing at least two NH, OH or SH groups.

The present invention relates also to the use of compounds of formula Iin the production of mass-coloured plastics or polymeric colourparticles and to the plastics or polymeric colour particles colouredusing the compounds of formula I.

The dyes according to the invention impart to the above-mentionedmaterials, especially polyester materials, level colour shades of hightinctorial strength that have good in-use fastness properties,especially very good high-temperature light fastness.

The dyes according to the invention can furthermore be used for coatingapplications of any kind.

The dyes according to the invention can also readily be used togetherwith other dyes to produce blended shades.

The anthraquinone dyes of formula (I) according to the invention arefurthermore suitable as colorants in the production of colour filters,especially for visible light in the range from 400 to 700 nm, for liquidcrystal displays (LCDs) or charge combined devices (CCDs).

The production of colour filters by sequential application of a red,blue and green colorant to a suitable substrate, for example amorphoussilicon, is described in GB-A 2 182 165. The colour filters can becoated, for example, using inks, especially printing inks, that comprisethe anthraquinone dyes according to the invention, or can be produced,for example, by blending the anthraquinone dyes according to theinvention with chemically, thermally or photolytically structurable highmolecular weight material. The further production can be carried out,for example, analogously to EP-A 654 711 by application to a substrate,such as an LCD, followed by photo-structuring and development. Otherdocuments that describe the production of colour filters include U.S.Pat. No. 5,624,467, Displays 14/2, 115 (1993) and WO 98/45756.

The colour filters that are produced for liquid crystal displays (LCDs)using the anthraquinone dyes according to the invention aredistinguished by high transmission of colour dots.

The invention relates also to the use of an anthraquinone dye accordingto the invention as a colorant in the production of colour filters.

The following Examples serve to illustrate the invention.

EXAMPLE 1 A. 1,5-Bis(2-hydroxyethylamino)3,7-dibromoanthraquinone

90 g of 1,3,5,7-tetrabromoanthraquinone, 142.3 g of 2-aminoethanol, 18.6g of sodium acetate and 0.52 g of copper(I) acetate are introduced intoa laboratory reaction apparatus and stirred for 3 hours at 130° C. Aftercooling to room temperature (RT), the reaction mixture is taken up inethanol and poured into water. After filtration and drying, 24 g (65%)of product are obtained.

B. 1,5-Bis(2-hydroxyethylamino)-3,7-bis(phenylmercapto)-anthraquinone

24 g of 1,5-bis(2-hydroxyethylamino)-3,7-dibromoanthraquinone areintroduced at RT into 100 ml of dimethylformamide (DMF). After theaddition of 16.3 g of sodium thiophenolate, the mixture is heated to120° C. and maintained at that temperature for one hour. After coolingthe mixture to RT, 100 ml of methanol are added thereto. The precipitateis filtered off, washed with a methanol/water mixture (1:1) and dried invacuo.

Yield: 18.6 g (68.5%)

EXAMPLE 2 A. 1,5-Bis(phenylamino)-3,7-dibromoanthraquinone

20 g of 1,3,5,7-tetrabromoanthraquinone, 70 ml of aniline, 9.3 g ofsodium acetate and 0.26 9 of copper(I) acetate are introduced into alaboratory reaction apparatus and stirred for 2 hours at 150° C. Aftercooling the mixture to RT, the crude product is precipitated usingethanol, filtered off, washed and dried in vacuo.

Yield: 16.8 g (80%)

B. 1,5-Bis(phenylamino)-3,7-bis(2-hydroxyethylmercapto)-anthraquinone

16.8 g of 1,5-bis(phenylamino)-3,7-dibromoanthraquinone and 5.6 g of2-hydroxyethylmercaptan are introduced at RT into 50 ml of DMF. Afterheating the mixture to 110° C., a solution of 8.16 g of potassiumtert-butanolate in 90 ml of DMF is added. The mixture is stirred for 2hours at 110° C. 500 ml of water are then added dropwise. Theprecipitate is filtered off, washed and dried in vacuo.

Yield: 11.4 g (70%)

EXAMPLE 3 A. 1,5-Bis(mesitylamino)-3,7-dibromoanthraquinone

37 g of 1,3,5,7-tetrabromoanthraquinone, 12.3 ml of mesidine, 17.3 g ofsodium acetate and 0.5 g of copper(I) acetate are introduced into alaboratory reaction apparatus and stirred for 7 hours at 170° C. Aftercooling to RT, the crude product is precipitated by the addition of 1litre of 2N HCl and recrystallised from ethanol. After filtration anddrying 21 g (47%) of product are obtained.

B. 1,5-Bis(mesitylamino)-3,7-bis(phenylmercapto)-anthraquinone

16.5 g of 1,5-bis(mesitylamino)-3,7-dibromoanthraquinone are suspendedat RT in 50 ml of DMF and heated to 120° C. After cooling to 50° C., asuspension of 8.5 g of sodium thiophenolate in 25 ml of DMF is addedthereto. The mixture is then heated to 120° C. again and stirred at thattemperature for 1.5 hours. After cooling the mixture to 60° C., 100 mlof methanol are added and the mixture is stirred overnight at RT. Theprecipitate is filtered off, washed with a methanol/water mixture (1:1)and dried in vacuo.

Yield: 11.2 g (62%)

EXAMPLE 4 1,3,5,7-Tetrakis(phenylmercapto)anthraquinone

90 g of 1,3,5,7-tetrabromoanthraquinone and 50 g of sodium thiophenolateare suspended at 70° C. in 150 ml of DMF in a laboratory reactionapparatus. The reaction mixture is stirred for 5 hours at 120° C. Aftercooling to RT, the precipitate is filtered off, washed with ethanol anddried in vacuo.

Yield: 22.6 g (73%)

II. APPLICATION EXAMPLES

II.1. Production of a Colour Filter for Liquid Crystal Displays (LCDs)

In a 100 ml glass vessel containing 83.3 g of zirconium ceramic beads,2.8 g of the anthraquinone dye according to Example 1, 0.28 g ofSolsperse® 5000, 4.10 g of Disperbyk® 161 (dispersing agent, 30%solution of a high molecular weight block copolymer, containing groupshaving affinity for the pigment, in n-butyl acetate/l -methoxy-2-propylacetate 1:6, BYK Chemie) and 14.62 g of 1-methoxy-2-propyl acetate (MPA)are stirred at 23° C. for 10 minutes at 1000 revs/min. and for 180minutes at 3000 revs/min. using a Dispermat. After the addition of 4.01g of an acrylate polymer binder (35% solution in MPA), stirring iscarried out at room temperature for 30 minutes at 3000 revs/min.Following removal of the beads, the dispersion is diluted with an equalweight of MPA.

Using a spin-coating apparatus, a glass substrate (Corning type 1737-F)is coated with the resulting dispersion and centrifuged for 30 secondsat 1000 revs/min. The layer is dried on a hot plate for 2 minutes at100° C. and for 5 minutes at 200° C. The resulting layer thickness is0.4 μm.

The following anthraquinone dyes (Table 1), which are likewise suitablefor mass-colouring plastics, can be prepared analogously to Example 1:TABLE 1 (I)

R₁ R₂ R₃ R₄

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

—NH₂

1. A compound of formula I

wherein R₁ and R₃ are each independently of the other —NHR₅, —NHSO₂R₅,—NHCOR₅, —OR₆ or —SR₇, R₂ and R₄ are each independently of the other—OR₆ or —SR₇, with the proviso that not all of the substituents R₁ to R₄are —SR₇, R₅ is hydrogen, alkyl, aryl, aralkyl or a group of formula—(C_(n)H_(2n)X)_(m)—H wherein X is —O—, —S—, —SO₂—, —NH—, —NR₈—, —CONH—or —CONR₈— and R₈ is alkyl or aryl, n is a number from 2 to 6 and m is anumber from 1 to 10, R₆ is aryl or heteroaryl and R₇ is alkyl, aryl,heteroaryl or a group of formula —(C_(n)H_(2n)X)_(m)—H wherein X is —O—,—S—, —SO₂—, —NH—, —NR₈—, —CONH— or —CONR₈— and R₈ is alkyl or aryl.
 2. Acompound of formula I according to claim 1 wherein R₁ and R₃ are —NHR₅or —SR₇ and R₅ and R₇ are as defined in claim
 1. 3. A compound offormula I according to claim 1 wherein R₁ and R₃ are —NHR₅ or —SR₇ andR₅ and R₇ are aryl or hydroxyalkyl.
 4. A compound of formula I accordingto claim 3 wherein R₅ is phenyl, mesityl or 2-hydroxyethyl and R₇ isphenyl.
 5. A compound of formula I according to claim 1 wherein R₂ andR₄ are —SR₇ and R₇ is as defined in claim
 1. 6. A compound of formula Iaccording to claim 5 wherein R₇ is aryl or hydroxyalkyl.
 7. A compoundof formula I according to claim 6 wherein R₇ is phenyl or2-hydroxyethyl.
 8. A compound of formula I according to claim 1according to any one of formulae Ia to Ic


9. A process for the preparation of a compound of formula I according toclaim 1 which comprises reacting 1,3,5,7-tetrabromoanthraquinone with acompound R₁—H or with a mixture of the compounds R₁—H and R₃—H in afirst reaction step, and then reacting the so-prepared intermediate witha compound R₂—H or with a mixture of the compounds R₂—H and R₄—H, R₁,R₂, R₃ and R₄ being as defined in claim
 1. 10. (canceled)
 11. A methodof producing mass-coloured plastics or polymeric colour particles thatcomprises mixing a high molecular weight organic material and atinctorially effective amount of at least one compound of formula I. 12.A method of producing mass-coloured plastics or polymeric colourparticles that comprises causing a mixture comprising at least onemonomer that contains at least one NH-, OH- or SH-reactive group and iscapable of polymerisation, polyaddition or polycondensation reactions toreact with at least one compound of formula I according to claim 1 thatcontains at least two NH, OH or SH groups.
 13. Plastics or polymericcolour particles coloured in accordance with a method according to claim11.
 14. (canceled)
 15. Plastics or polymeric colour particles colouredin accordance with a method according to claim
 12. 16. A method ofproducing colour filters that comprises coating a substrate with a highmolecular weight organic material that contains a tinctorially effectiveamount of at least one compound of formula (I) according to claim 1.